The DNA-protein interactions involved in the regulation of the biotin (bio) operon of Escherichia coli will be studied. The relationships between promoter sequence and promoter function will be studied by in vitro mutagenesis using chemically synthesized oligonucleotides. The interaction between the bifunctional biotin operon repressor/biotin activating enzyme (BirA) and bio operator DNA will be analysed by genetic and biochemical methods. The long term objective of the project is to understand the precise mechanisms of bacterial gene regulation, with special regard to sequence-specific DNA-protein interactions. The data obtained may be applied to problems of gene evolution, bacterial metabolism, expression of synthetic genes and specific regulation of gene expression is Escherichia coli.